We've got the FUNk, gotta love that FUNk but with HOT CODES

[323kielr]

Hi all,

I would like your thoughts.
I have a 96 5.7 vortec in a suburban.

Codes:
All the O2 codes that I have always had and are never an issue. I just leave them since I have no emissions check.
New codes;
P13151- circuit control open
P0102- MAF circuit low
P0108- manifold pressure circuit high


Symptoms:
Runs and drives great for 30 min, then sputters and dies, no hot restart.

Once it cools (overnight) it runs and drives great for another 30 min.

I have maintained it well, replaced fuel pump, ignition components and blah blah lists...

This is our family rig and we plan to keep it on the road. Just not sure what is happening right now.

Although I have replaced worn components, I know some replacement parts can be cheap and fail prematurely.

Thanks for your help.

 

[Orpedcrow]

What are your O2 codes? Sounds like maybe it’s not getting what it needs in closed loop. MAF and MAP issues might be compounding that.

Edit: p1351 is for the ignition control module I believe.

There’s several things it could be but the MAF, MAP and ICM circuits are all in the same harness and close to each other.

 

[Schurkey]

NOT addressing O2 sensors is a big mistake. You're probably throwing away power, fuel economy, and emissions compliance; not to mention the possibility of over-fueling washing the oil off the cylinder walls leading to excess engine wear.

Download the service manual set for your vehicle from the links in the Sticky section. Follow the diagnostic procedure for each trouble code.

Runs reliably for ~30 minutes, then stalls and won't re-start:
Ignition module overheating is possible, not hugely likely.
Ignition coil overheating is possible, not hugely likely.
Pickup coil issues--possible, not at all likely given those symptoms.
For all of the above--do you have spark after the engine stalls?

Fuel tank not venting, developing a vacuum, and making fuel delivery difficult is a possibility.
Do you have proper fuel pressure after the engine stalls?

If the O2 sensors have been ignored for ages...how old is the fuel filter, spark plugs, plug wires, distributor cap 'n' rotor?

 

[2drXmobb]

Try running the engine and unplug your map sensor check if it changes idle. Might be a bad sensor or swap it out for another there expensive tho if you have a friend or junkyard just wear baggy clothes and pay your $2 fee

 

[323kielr]

Thank you all for the input.

I suppose I should address the O2 sensors, it has been fine for 4 years, but I understand it should be addressed.

I swaped the coil, no change, fuel pump 2 years ago, cap and rotor was done 2 months ago with plugs. I tested my ignition control module two months ago, and it was fine, but it could have failed with the new coil maybe?

I will check fuel pressure, and spark (under crank after stall)

I will also try and remove the gas cap when stalling to see if that helps.


Updates coming soon.

 

[323kielr]

Changed the ignition control module and it runs as it should. So far at least.

Hot restart went fine. I will test the old icm as t a parts store next week.